The suspects later fled across the border to Tachilek on May 25, the day Ms Warisara’s body was discovered, they added.

The three suspects then applied to work as bar girls at a karaoke bar, owned by a Thai business operator, in the Myanmar town, which is opposite Chiang Rai’s Mae Sai district.

Deputy Provincial Police Region 4 chief Charoenwit Siwanit said yesterday (June 2) that a joint investigation with Myanmar authorities suggested the trio were likely accompanied by three men who were bar customers.

A police source said one of the men was identified as being called “Kao”. The three suspects are believed to have left Tachilek on the night of May 28 or early on May 29.

Myanmar authorities are searching north of Tachilek, in particular, Mong Ko which is 60 kilometres away, as Mr Kao has a wife there. However, the suspects may have travelled further to Kengtung in Shan State, the source said.

Preeyanuch contacted her friend and sister in Thailand via a Line application on Thursday night (June 1), saying she and her two friends were safe, said Col Pongrit Kongsirisombat, a superintendent of the Provincial Police Region 4.

This has led police to believe someone in Myanmar might have helped the women escape and give them shelter, he said.

Besides the three women, two other suspects, Wasin Namprom, 22, and his girlfriend Jidarat Promkhun, 21, are already in police custody.

Meanwhile, Office of the Narcotics Control Board (ONCB) secretary-general Sirinya Sitdhichai said Preeyanuch, who is accused of throttling and dismembering Ms Warisara, may be linked to a drug ring in the “golden triangle” area.

“A few years ago she was arrested for possession and use of an illegal drug and the ONCB later found out she had contacts with a big drug cartel that smuggles drugs into Thailand from the golden triangle area of Myanmar,” he said.

The ONCB was trying to suppress the cartel’s activities, but have yet to ascertain whether Preeyanuch’s part was to collect money or lure customers, he said.

Mr Sirinya, however, does not think Ms Warisara was murdered on the cartel’s orders to prevent authorities from rounding up more members of the gang.

Police assume Ms Warisara’s murder stemmed from a personal conflict as the victim had informed police of wrongdoing which later led to the arrest of Preeyanuch’s husband who is now in prison.